1. Field of the Invention
This invention relates to seals for enabling wire to be fed continuously through a wall separating regions of different pressures and to apparatus using such seals.
Such seals are required, for example, in apparatus where the wire is subjected to a treatment, for example heat treatment or coating, which has to be carried out in a vacuum and where the treatment is to be carried out as a continuous operation. The seals enable the wire to be continuously fed through a vacuum closure and hence permit of a continuous process operation.
2. Prior Art
In the U.S. Pat. No. 3,952,568 there is described and claimed a seal permitting the feeding of material of predetermined uniform section through a wall separating regions of different pressures comprising a pair of die-shaped elements located in spaced holders, said die-shaped elements being of hard rigid material and having a bore with clearance for the passage of said rod or wire material, said die-shaped elements furthermore being smoothly curved in any axial section to have a convergent entry portion leading to the narrowest portion and a divergent exit portion, a tube sealed between said holders and a removable insert in said tube externally fitting closely within the tube and having a longitudinal bore for the passage of the rod or wire material.